This invention relates to label printing, and more particularly to a method and apparatus for multi-impression printing of labels having pressure sensitive adhesive.
Pressure sensitive labels provide many advantages, but also many problems, one of which is protecting the adhesive until ready for use. Much effort has been devoted to surmounting these problems, as shown generally, for example, in the devices of Canadian Pat. No. 795,643. Another reference, U.S. Pat. No. 3,556,898, assigned to the assignee of the present invention, discloses a Label Printing and Dispensing Apparatus directed to printing and issuing pressure sensitive labels in an automatic computing scale system.
In order to reduce costs and improve efficiencies, many merchandising operations use automatic computing scale systems to weigh each product portion automatically, calculate the price, and issue an appropriately printed label. When the amount of "variable" information is small, prior art devices have printed pressure sensitive labels quite satisfactorily. However, when large amounts of variable information are printed, difficulties may arise since the printing must normally be completed before the label is removed from its release web (commonly some type of waxy paper). It is therefore common practice to print as much information as possible just before the label and release web are separated and the label is ejected from the machine. Thus the printing station becomes quite crowded and complicated.
Alternatively, several printing stations may be used, and this has been done with labels using adhesives which are not immediately active (e.g., heat activated), since the individual labels may be moved easily from one printing station to the next. However, since pressure sensitive labels are not normally removed from the release web until all printing is completed, such labels have not been separately advanced through such prior art multiple printing stations. Thus, several such labels are effectively pre-printed upstream and must then be purged each time the variable information is changed at any but the last printing station. Further, means (or personnel) must identify which label or ticket is actually the correct one. Depending on the circumstances, this can be quite costly, especially where the user's label needs change frequently throughout the day.